The present invention relates to a radio terminal such as a portable radio communication terminal for acquiring contents on the Internet, an information processing system using the radio terminal, and an external processing terminal connected to the radio terminal to assist the radio terminal.
In recent years, the Internet becomes popular to allow taking advantage of many opportunities to acquire contents from a content server on the WWW (World Wide Web) to obtain various kinds of information or do shopping on the Internet. Such use of the Internet greatly increases along with the spread of portable terminals such as a PHS (Personal Handyphone System) or portable telephone.
As shown in FIG. 14, in an information processing system using a conventional portable terminal, a content server 102 and portable telephone network 103 are connected to the Internet 101. A portable radio communication terminal (to be referred to as a portable terminal hereinafter) 104 is connected to the portable telephone network 103. The content server 102 accommodates various contents written in a document description language such as an HTML (HyperText Markup Language) or XML (Extensible Markup Language). The portable terminal 104 accesses the portable telephone network 103, thereby displaying these contents on its display device or outputting a voice as part of the contents of the contents.
As shown in FIG. 15, the portable terminal 104 comprises a CPU (Central Processing Unit) 111, and a program memory 113, data processing section 114, content analysis section 116, content memory 117, voice processing section 118, and display processing section 121 connected to the CPU 111 through a bus 112 such as a data bus. These components 113, 114, 116, 117, 118, and 121 are connected to the CPU 111 through the bus 112 such as a data bus. The portable terminal 104 also has a radio section 115 connected to the data processing section 114, a speaker 119 connected to the voice processing section 118, and a display device 122 connected to the display processing section 121.
The program memory 113 stores a program which is executed by the CPU 111 to implement various functions of the portable terminal 104. The data processing section 114 is connected to the portable telephone network 103 (FIG. 14) by radio to transmit/receive data. The content analysis section 116 analyzes the contents of contents received from the content server 102 (FIG. 15) through the data processing section 114. The content memory 117 stores necessaries of acquired contents. The voice processing section 118 processes voice data in acquired contents and outputs the voice data from the speaker 119. The display processing section 121 processes image data in acquired contents and displays the image data on the display device 122 such as a liquid crystal display device.
The block diagram of the portable terminal shown in FIG. 15 does not illustrate a known technique but is shown for the descriptive convenience.
Processing from a content request by the portable terminal of the above-described information processing system to image display will be described next with reference to FIG. 16. In acquiring a content, in accordance with operator's operation on the portable terminal 104, the CPU 111 of the portable terminal 104 requests, through the portable telephone network 103, the content server 102 on the network to acquire data related to the content (step S131). In response to this request, the content server 102 returns data related to the requested content to the portable terminal 104 (step S132).
The CPU 111 sends requests for data acquisition a plurality of number of times depending on the content (step S133). The content server 102 returns data related to the requested content to the portable terminal 104 in response to each request (step S134). The CPU 111 sequentially stores the returned data in the content memory 117.
When all data related to the requested content are completely received, the content analysis section 116 analyzes the content stored in the content memory 117. On the basis of the analysis result, the CPU 111 requests the display processing section 121 to execute display processing for data to be displayed on the display device 122 (step S135). Thus, the content is displayed on the display device 122.
A portable terminal such as a portable telephone must be compact and lightweight for portability. For this reason, as compared to a normal desktop computer, the capacity of the internal memory, the processing speed of the CPU 111, or the screen size of the display device 122 is considerably limited.
Japanese Patent Laid-Open No. 11-168425 has proposed to reduce the capacity of a memory to be used by replacing tag information contained in the document description language with simple compressed information. In this proposal, a database related to tag information is prepared in a portable terminal to compress/decompress tag information.
However, contents are increasingly becoming complex and large as various media are developed. For this reason, it is difficult to update the database itself, which is related to tag information. In addition, a memory capacity larger than the capacity that can be saved by compressing tag information is required to store contents. However, it is not practical to improve the capability of the portable terminal to meet the requirement because the terminal itself becomes bulky and expensive.
Contents are becoming more complex along with the sophistication of requests for contents. Hence, even when a portable terminal has a sufficient capability at certain time, it is often difficult to reconstruct a state-of-the-art content after the elapse of years from the purchase time.
Dedicated contents are created for such portable terminals with a less capability than a normal computer. However, when contents for portable terminals are created and provided aiming at a low-end portable terminal of various kinds of portable terminals, a portable terminal having a relatively high capability cannot take advantage of advanced contents. It is also difficult for the content provider side to create many types of contents according to the capabilities of individual portable terminals.
Furthermore, a portable terminal is poor in security as compared to a normal computer such as a desktop computer. This will be described in accordance with comparison between a normal computer and a portable terminal.
A conventional information processing system using the Internet will be described next with reference to FIG. 17. Computers 2021 to 202A and a plurality of WTA (Wireless Telephony Application) servers 2031 to 203B of conventional type are connected to the Internet 201 through a router (not shown). Gateways 2051 to 205D are connected to the Internet 201. Portable terminals 2071 to 207F are connected to the gateways 2051 to 205D through base stations 2061 to 206E. Each of symbols A to F represents an arbitrary positive value of 2 or more.
In this information processing system, assume that the first computer 2021 accesses a content as data stored in the first WTA server 2031. In this case, the first computer 2021 designates the URL (Uniform Resource Locator) of the content to be accessed. Communication for browsing the content on the WWW is performed using a communication protocol called the HTTP (HyperText Transfer Protocol). More specifically, the first computer 2021 transmits the URL of the HTML document to be displayed as a request. In response to this, the first WTA server 2031 transmits the corresponding HTML document to the first computer 2021 as a client. In this communication protocol, the computer is connected to the first WTA server 2031 every time communication data is to be acquired, and disconnected when reception of communication data is ended.
A case wherein the first portable terminal 2071 in the portable terminals 2071 to 207F accesses the first WTA server 2031 will be described next. In this case, a communication protocol called the HTTP is used between the first WTA server 2031 and the first gateway 2051 connected to the first portable terminal 2071, like the case wherein the computers 2021 to 202A access the WTA server 2031 to 203B of conventional type. In the WAP (Wireless Application Protocol), a protocol called the WSP (Wireless Session Protocol) is used between the second gateway 2052 and the second portable terminal 2072.
The WAP is a protocol for obtaining Internet information from a portable terminal using a telephone network. In this case, information is obtained from the WWW using the WML (Wireless Markup Language) similar to the HTML.
FIG. 18 shows communication between a computer and a WTA server of conventional type in the above-described information processing system. The computer 202 and WTA server 203 communicates various kinds of data such as data written in the description language HTML or GIF (Graphics Interchange Format) or BMP (BitMaP) data using the HTTP.
FIG. 19 shows communication between a portable terminal and a WTA server of conventional type. Communication using the HTTP is performed between the WTA server 203 and the gateway 205, as in FIG. 18. On the other hand, a communication method different from that in FIG. 18 is used between the portable terminal 207 and the gateway 205, considering that the capacity of the internal memory of the portable terminal 207 is small, or no high-speed CPU can be mounted for power saving or space saving. The WAP described above has received a great deal of attention as a communication method in this section.
In the WAP, a description language called the HTML sent from the WTA server 203 is sent to the gateway 205, where the display position of an image by GIF data or the like is calculated. The data is converted into data that can be actually displayed on two windows of the portable terminal 207 and sent to the portable terminal 207 as binary data. This transfer is done using a protocol called the WSP (Wireless Session Protocol).
To transmit information using a network, the security of communication must be taken into consideration. Between the computer 202 and WTA server 203 shown in FIG. 18, the SSL (Secure Socket Layer) or TLS (Transport Layer Security) is used for encryption or authentication, thereby ensuring the security of communication. The SSL is a protocol for implementing encryption and authentication function at socket level. The TLS is a security protocol that is replacing the SSL. These protocols almost equal and sometimes expressed as TLS/SSL. This expression will be used in the following description.
The TLS/SSL is also used between the computer 202 and the WTA server 203 shown in FIG. 19. Between the portable terminal 207 and the gateway 205, a protocol called the WTLS (Wireless Transport Layer Security) is used. This protocol has the same function as that of the TLS as the Internet standard and is optimized for the portable terminal 207. This protocol also has the encryption, authentication, and compression functions.
When the above-described encryption technique is employed, the security of communication data is ensured between the computer 202 and the WTA server 203 shown in FIG. 18. Like the computer 202 and WTA server 203 shown in FIG. 18, the gateway 205 and WTA server 203, and the gateway 205 and portable terminal 207 also ensure the security of communication therebetween. However, in the latter information processing system, encrypted communication data is temporarily decrypted by the gateway 205 and then encrypted using another protocol. Hence, the presence of the gateway 205 as the relay point between two points of data transmission is a blind spot in ensuring the security of communication.
Two problems are posed in ensuring the security of communication at the gateway 205. As the first problem, the gateway 205 may be attacked by a third party to alter or thieve communication data transmitted between the WTA server 203 and the portable terminal 207. As the second problem, the manager of the gateway 205 may see or alter communication data that is not secured in communication.
Various proposals have been made to solve the former problem. For example, invasion of a malicious third party is prevented using a fire wall, as described in Japanese Patent Laid-Open Nos. 10-200530, 10-285216, and 11-146016. However, this countermeasure is not perfect because communication data can be transmitted while detouring the network by tunneling processing. For the latter problem, since encrypted communication data is decrypted by the gateway 205 for the next encryption, one must presently expect morals of the manager of the gateway 205.
As described above, the security of end-to-end communication cannot be ensured between the portable terminal and the server on the network because the natures of the transmission paths therebetween are different up to the gateway between the paths.
A portable terminal and an information processing system using the portable terminal have been described above. A portable terminal having a relatively low processing capability also has the same problems as described above.